CN1886161A - Rotary blood pump - Google Patents

Abstract

Various "non-contact" bearing mechanisms including hydrodynamic and magnetic bearings are available for use in rotary pumps in place of mechanical contact bearings. In one embodiment, a pump apparatus includes a pump housing (110) defining a pump chamber (112). The pump housing has a spindle extending into the pump chamber. The spindle has a spindle magnet assembly (160) therein that includes first and second magnets (262, 264). The first and second magnets are positioned in close proximity to each other with their magnetic vectors opposing each other. Because mechanical contact bearings are not used, the pump has an extended service life and less damage to the working fluid, such as blood.

Description

rotary blood pump

field of invention

This invention relates to rotary pumps. In particular it relates to bearings for various rotor and impeller configurations.

Background of the invention

Typical rotary pumps use an impeller where the motion of the impeller is constrained in five degrees of freedom (two angular, three translational) with mechanical contact bearings. Some working fluids can be damaged by mechanical contact bearings. Blood pumped by a pump with contact bearings undergoes hemolysis, the destruction of blood cells. In general, certain applications require the use of highly efficient hydraulic and high powered pumps capable of pumping delicately handled working fluids such as blood.

US Patent No. 6,234,772 B1 to Wampler et al. ("Wampler") describes a centrifugal blood pump having radial magnetic repulsion bearings and axial hydrodynamic bearings. US Patent No. 6,250,880 B1 to Woodard et al. ("Woodard") describes a centrifugal blood pump whose impeller is supported solely by hydrodynamic forces.

Both blood pumps are based on an axial flux gap motor design. The drive magnets of the motor are carried in the impeller, which acts as the motor rotor. In both cases, the drive magnets are located in the blades of the impeller. The location of the drive windings is outside the pump but inside the pump casing which acts as the motor stator. Since the motor is integrated with the pump, sealing of the drive shaft and pump is omitted. The pump/motor includes a back iron that enhances the magnetic flux used to drive the impeller.

The problem with both blood pumps is hydraulic inadequacy, at least in part due to the large and unconventional blade geometry required to place the magnets in the impeller blades.

For the pump to work effectively, it must overcome the strong natural axial attraction between the magnets carried by the vanes and the back iron. Although no contact occurs between the vanes and the pump housing, hydrodynamic bearings can cause destruction of blood cells due to shear forces associated with the loads carried by the hydrodynamic bearings. So using only hydrodynamic bearings may be harmful to the blood.

SUMMARY OF THE INVENTION

In view of the deficiencies of known blood pumps and methods, rotary pumps have replaced mechanical contact bearings with various "non-contact" bearing mechanisms. Magnetic and hydrodynamic bearings are implemented with various rotor and housing design features. These design features can be combined. Since mechanical contact bearings are not used, the service life of the pump is extended and the damage to the working fluid such as blood is reduced.

In one embodiment, the pump includes a magnetic thrust bearing. The pump includes a pump housing defining a pump chamber. The pump housing has a spindle extending into the pump chamber. The spindle is provided with a spindle magnet assembly including first and second magnets. The first and second magnets of the spindle magnet assembly are located adjacent to each other and have opposite magnetic vectors. The pump includes a rotor with an impeller rotatable about the spindle. A rotor magnet assembly including first and second magnets is disposed in the non-blade portion of the rotor. The first and second magnets of the rotor magnet assembly are positioned adjacent to each other and have opposite magnetic vectors. The relative orientation of the mandrel and rotor magnet assemblies is selected such that the mandrel and rotor magnet assemblies attract each other. The rotor may include a slotted bore. In various embodiments, hydrodynamic bearings are included for radial support or axial support or radial and axial support.

Brief description of the drawings

The present invention is illustrated below in conjunction with illustrative accompanying drawings, and in each accompanying drawing, identical parts are represented with identical reference numerals, and among accompanying drawings:

Figure 1 is a sectional view of a pump with a passive axial magnetic bearing;

Figure 2 shows an embodiment of the passive axial magnetic bearing;

Figure 3 shows the central and eccentric arrangement of the passive axial magnetic bearing;

Figure 4 shows an impeller embodiment; and

Figure 5 shows an embodiment of the pump used in medicine.

Detailed description

Figure 1 shows an embodiment of a centrifugal blood pump. The pump includes a housing 110 defining a pump chamber 112 between an inlet 114 and an outlet 116 . In the pump chamber, a rotor 120 rotates about a spindle 130 protruding from the bottom of the pump housing. The rotor also includes a blade portion defining an impeller providing a fluid flow surface. The impeller includes one or more blades 121 that push fluid as the impeller rotates.

"Rotor" and "impeller" mean the same thing in some contexts. For example, when the rotor rotates, the blades of the rotor also rotate, so it can be said that the rotor rotates or the impeller rotates. However, "non-blade portion of the rotor" or "rotor other than the impeller" can be used to refer to the part of the rotor other than the blades when necessary. Each blade of the rotor can be called an impeller, but an impeller generally refers to a collection of one or more blades.

The pump is built on a moving magnet axial flux gap motor construction. In one embodiment, the motor is a brushless DC motor. The magnetic vectors of the magnets 122 in the rotor are parallel to the rotor axis of rotation 190 . In the illustrated embodiment, the drive magnets are located in the non-bladed portion of the rotor.

Drive windings 140 are located within the pump housing. Electricity is applied to the drive windings to generate a time-dependent current that interacts with the drive magnets, causing the impeller to rotate. A back iron 150 enhances the magnetic flux generated by the rotor magnets of the motor. In one embodiment, the rotor bottom surface 124 or the opposing surface 118 of the lower pump housing has a surface (such as 172) that forms a hydrodynamic bearing when the clearance between the rotor and the housing is less than a predetermined threshold. In one embodiment, the predetermined threshold is 0.0002-0.003 inches.

The natural attraction between the back iron 150 and the drive magnets 122 carried by the rotor generates significant axial loads on the rotor. This axial load is present in centrifugal pumps of axial flux gap motor construction such as Wampler or Woodard. Both Wampler and Woodard rely on hydrodynamic thrust bearings to overcome this axial load force. Although no contact occurs between the vanes and the pump housing, hydrodynamic bearings can cause destruction of blood cells due to shear forces associated with the loads carried by the hydrodynamic bearings.

Wampler's Radial Repulsion Magnetic Bearings accentuate the axial force generated by the magnetic attraction between the drive magnet and the back iron. Although radially repulsive magnetic bearings generate radial stability, they cause significant axial instability. This axial instability can further increase the axial load. Regardless of the axial hydrodynamic bearing used, this additional axial force causes greater shear forces, resulting in blood cell lysis. Furthermore, the power required to maintain the hydrodynamic bearing increases with this load. Therefore, the power consumption of the hydrodynamic bearing with high load is large.

The blood pump of FIG. 1 includes an axial magnetic bearing to reduce or counteract the axial load on the rotor caused by the interaction between the drive magnet and the back iron. The axial magnetic bearing is formed by the interaction between a spindle magnet assembly 160 located within the spindle and a rotor magnet assembly 180 carried by the rotor. In the illustrated embodiment, the rotor magnet assembly 180 is adjacent to the impeller, but the magnets of the rotor magnet assembly are not located in the blades. Adjustment screw 134 adjusts the axial position of the axial magnetic bearing longitudinally by moving the spindle magnet assembly on the longitudinal axis of the spindle.

Figure 2 shows an axial magnetic bearing embodiment. The rotor magnet assembly includes a first rotor bearing magnet 282 and a second rotor bearing magnet 284 adjacent to each other. The first and second rotor bearing magnets are permanent magnets. In one embodiment, there is a pole piece 286 between them. Pole pieces or flux concentrators are used to concentrate the magnetic flux generated by rotor bearing magnets 282 and 284 . In another embodiment, the member 286 is just a spacer to help position the first and second bearing magnets 282, 284 and not to concentrate the magnetic flux. In other embodiments, component 286 is omitted so that the rotor magnet assembly does not include spacer or pole piece components.

In one embodiment, members 282 and 284 are a single piece of annular permanent magnet. The bearing magnets can also be in non-monolithic compositions. For example, the bearing magnet can also be in the form of a ring-shaped permanent magnet structure composed of multiple pie-shaped, arc-shaped or other shaped permanent magnets.

The rotor axial bearing magnet assembly is distinct from the drive magnets 222 in the non-blade 221 portion of the rotor. In the illustrated embodiment, the drive magnets are located in the non-bladed portion 228 of the rotor.

The spindle magnet assembly includes a first spindle bearing magnet 262 and a second spindle bearing magnet 264 . The first and second rotor bearing magnets are permanent magnets. In one embodiment, there is a pole piece 266 between them. Pole piece 266 collects the magnetic flux generated by hub bearing magnets 262 and 264 . In another embodiment, member 266 simply acts as a spacer for the positioning of the first and second spindle bearing magnets and does not serve to concentrate the magnetic flux. In other embodiments, component 266 is omitted so that the spindle magnet assembly does not include spacer or pole piece components.

In the illustrated embodiment, the permanent magnets 262 and 264 have a cylindrical shape. Other shapes may also be used in other embodiments. The annular rotor magnet rotates with the impeller about the spindle longitudinal axis used by the spindle bearing magnet assembly.

The permanent magnets of the spindle and rotor bearing assembly are arranged such that the magnetic vectors of the magnets on either side of the center pole piece are opposite to each other.

Both sides of a given pole piece abut the same pole of a different magnet.

Therefore, the magnetic vectors of magnets 262 and 264 are opposite to each other (eg, N to N or S to S). Likewise, the magnetic vectors of magnets 282 and 284 are opposite to each other.

The orientation of each magnet is chosen to create an axial attraction whenever the bearing is axially misaligned. Note that the relative orientation of the mandrel and rotor magnet assemblies is selected such that the mandrel and rotor magnet assemblies attract each other (eg, S to N, N to S). The magnetic vector direction chosen for the magnets of one assembly determines the magnetic vector direction for the magnets of the other assembly. Table 292 shows acceptable magnetic vector combinations for the first and second rotor bearing magnets (MR1, MR2) and the first and second spindle bearing magnets (MS1, MS2). Attractive magnetic forces between the back iron and the drive magnets that axially displace the magnetic bearing assembly are at least partially counteracted by axial magnetic forces between the axial bearings that restore the axial position of the rotor.

Figure 2 also shows a wedge or slope 272 forming part of a hydrodynamic bearing when the clearance between the non-vane side of the rotor (see eg bottom surface 124 in Figure 1) and the back of the pump housing is less than a predetermined threshold. In various embodiments, the predetermined threshold is 0.0002-0.003 inches. Thus, in one embodiment, the pump includes an axial hydrodynamic bearing. The surface geometry providing this axial hydrodynamic bearing can be on the rotor or the housing.

Although the spindle magnet assembly acts as an axial magnetic bearing, the attractive force between the spindle and rotor magnet assembly also has a radial component. This radial component can be used to counteract the radial load on the impeller caused by the pressure gradient across the impeller. This radial component also acts as a preload during initial rotation and as a biasing force against eccentric rotation of the rotor about the spindle during normal rotation. Eccentric rotation can cause fluid swirls or swirls that are detrimental to pumping action. This offset radial component helps to maintain or restore the radial position and pumping action of the rotor when the pump is subjected to external forces, eg, caused by movement or impact.

In other embodiments the magnetic bearing may be formed without a mandrel magnet assembly interacting with the rotor bearing magnet assembly and ferromagnetic material may be used instead of either a) the mandrel magnet assembly or b) the rotor bearing magnet assembly (but not both) spindle magnet assembly and rotor bearing magnet assembly).

The magnetic bearing still consists of a mandrel part and a rotor part, but one of the mandrel part and the rotor part uses ferromagnetic material and the other part uses permanent magnets.

The ferromagnetic material interacts with the magnets to create a magnetic attraction between the rotor and the spindle. Examples of ferromagnetic materials include iron, nickel and cobalt.

In one embodiment, the ferromagnetic material is "soft iron". Soft iron is characterized in part by an extremely low coercivity. Soft iron is therefore easily magnetized (or remagnetized) under the action of an external magnetic field, such as that of the permanent magnets of the magnetic bearing system, regardless of its remanence.

FIG. 3 shows various installation positions of the magnetic bearing spindle portion. In one embodiment, the axial direction of the mandrel magnet assembly 360 coincides with the longitudinal axis 390 of the mandrel, so that the longitudinal center axes of the mandrel and the mandrel magnet assembly are the same. In another embodiment, the spindle magnet assemblies are radially offset such that the central axes of the spindle and spindle magnet assemblies are different. In particular, the longitudinal axis 362 of the mandrel magnet assembly 360 is offset from the longitudinal axis 390 of the mandrel. This latter position setting can be used to create some radial biasing force if desired. The pressure differential across the impeller pushes the impeller radially to one side of the pump casing. This radial force is at least partially counteracted by offsetting the mandrel magnet assembly.

Although the spindle and rotor magnet assemblies are shown each comprising 2 magnetic elements, the magnet assemblies could each comprise a single magnet. Using multiple magnetic elements per assembly instead of a single magnet increases the spring rate. Bearings produced using two magnetic elements per assembly can correct for displacement from a stable position (ie displacement above and below the point of stability) in both positive and negative axial directions with a greater spring rate than using a single magnetic element per assembly.

The magnetic force generated by axial magnetic bearings has a radial component in addition to the axial component. This radial component can cause instability of the impeller. In particular, this radial component can cause instability in the radial position of the Figure 1 or 2 magnetic bearing.

This radial instability can be overcome using radial hydrodynamic bearings. Referring to Fig. 1, the pump can be designed with a radial hydrodynamic bearing (ie hydrodynamic sliding bearing) between the spindle 130 and the rotor along the rotor bore. The gap shown in Figure 1 is exaggerated. Hydrodynamic plain bearings require very small clearances to work. In various embodiments, the hydrodynamic journal bearing clearance is 0.0005-0.020 inches.

Surface geometries that can be used as axial (thrust) or radial (sliding) hydrodynamic bearings can be located on the rotor or on relevant parts of the housing (or mandrel). In one embodiment, the surface geometry includes features such as one or more pads (ie, a feature that creates a discontinuity in the gap such as a step of uniform height). In another embodiment, the surface geometry includes features such as one or more slopes.

Figure 4 shows an embodiment of a rotor comprising an impeller. The impeller includes a plurality of blades 420 for pumping a working fluid such as blood. The rotor includes a bore 410 . The rotor bore is coaxial with the longitudinal axis of the spindle in the pump housing. The drive magnets (not shown) are located within the non-blade portion 430 of the rotor (ie within the rotor but not within any blades of the rotor wheel portion). The motor rotor and impeller are therefore integrated, eliminating the need for a drive shaft. Without a drive shaft there is no need for a shaft seal.

In one embodiment, the rotor hole is slotted. In particular, the hole has one or more helical grooves. The slots have a non-zero axial pitch. The groove communicates with the working fluid of the pump when the pump is in operation.

FIG. 5 illustrates pump 510 operating to deliver working fluid 540 from a working fluid source 520 to a working fluid destination 530 . A first working fluid conduit 522 connects the source with the pump inlet 514 . A second working fluid conduit 532 connects the pump outlet 516 to the destination. A pump conveys working fluid from the source to the destination. In medicine, the working fluid is, for example, blood. In one embodiment, the source and the destination are arteries, so the pump transfers blood from one artery to the other.

Various "non-contact" bearings that can replace the mechanical contact bearings of rotary pumps have been described above. In particular, hydrodynamic or magnetic bearings are realized with rotors, impellers and housings of various designs. These designs can be used in combination when needed.

The present invention has been described in detail above in conjunction with specific exemplary embodiments. However, various modifications and changes can be made within the spirit and scope of the present invention as defined by the claims. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

Claims (68)

1. A pump device comprising: a pump casing (110) defining a pump chamber (112), the pump casing having a spindle (130) extending into the pump chamber; A spindle magnet assembly (160) of first and second magnets (262, 264), wherein the first and second magnets are positioned adjacent to each other and have opposite magnetic vectors. 2. The pump unit of claim 1, wherein the first and second spindle magnets have a cylindrical or annular form factor. 3. The pump apparatus of claim 1, wherein the spindle magnet assembly further includes a pole piece (266) positioned between the first and second magnets. 4. The pump device of claim 1, wherein the longitudinal axis (362) of the spindle magnet assembly is offset from the longitudinal axis (390) of the spindle. 5. The pump unit of claim 1, wherein at least one of the housing and the spindle has a surface geometry adapted to support at least one hydrodynamic bearing. 6. A pump unit as claimed in claim 5, characterized in that the spindle supports radial hydrodynamic bearings between the spindle and the bore of the rotor. 7. The pump unit of claim 5, wherein the at least one hydrodynamic bearing comprises an axial hydrodynamic bearing. 8. The pump device of claim 1, further comprising: a rotor rotatable about a spindle, the rotor including an impeller including at least one blade (121). 9. The pump apparatus of claim 8, wherein the rotor further comprises: a rotor magnet assembly (180) including first and second magnets (282, 284) disposed within the non-vane portion of the rotor; The first and second magnets are located immediately adjacent each other and have opposite magnetic vectors; the relative orientation of the mandrel and rotor magnet assembly is selected such that the mandrel and rotor magnet assembly attract each other. 10. The pump apparatus of claim 9, wherein the rotor magnet assembly further includes a pole piece (286) positioned between the first and second magnets. 11. The pump apparatus of claim 9, wherein at least one of the first and second rotor magnets has an annular form factor. 12. The pump apparatus of claim 9, wherein the first and second rotor magnets are concentrically disposed about the rotor bore. 13. The pump apparatus of claim 8, wherein at least one of the housing, the shaft and the rotor has a surface geometry operable to support at least one hydrodynamic bearing. 14. The pump unit of claim 13, wherein the at least one hydrodynamic bearing comprises a radial hydrodynamic bearing between the spindle and the bore of the rotor. 15. The pump unit of claim 13, wherein the at least one hydrodynamic bearing comprises an axial hydrodynamic bearing. 16. The pump device as claimed in claim 8, characterized in that the bore (410) of the rotor is slotted (450). 17. The pump device according to claim 8, characterized in that it further comprises: a plurality of driving magnets (122) carried by the non-blade portion of the rotor; and a driving winding (140) carried by the pump casing, wherein the driving magnets are connected with The drive windings cooperate to turn the rotor. 18. A pump device comprising: a rotor (120) having a hole (410), the rotor comprising an impeller having at least one vane (121); and a first and second magnet (282, 284) provided in the rotor ) rotor magnet assembly (180), wherein the first and second magnets are positioned adjacent to each other and their magnetic vectors are opposite. 19. The pump apparatus of claim 18, wherein the rotor magnet assembly further includes a pole piece (286) positioned between the first and second magnets. 20. The pump apparatus of claim 18 wherein at least one of the first and second rotor magnets has an annular form factor. 21. The pump apparatus of claim 18 wherein the first and second rotor magnets are concentrically disposed about the longitudinal axis of the rotor bore. 22. The pump unit of claim 18, wherein the rotor has a surface geometry adapted to support at least one hydrodynamic bearing. 23. The pump unit of claim 22, wherein the rotor bore provides a radial hydrodynamic bearing surface. 24. The pump unit of claim 22, wherein the at least one hydrodynamic bearing comprises an axial hydrodynamic bearing. 25. A pump device comprising: a pump housing (110) delimiting a pump chamber (112), the pump housing having a spindle (130) protruding into the pump chamber; rotatable around the spindle (130) A rotor (120) comprising an impeller having at least one blade (121); a rotor portion (180) of a magnetic bearing disposed within a non-blade portion of the rotor; and a spindle portion of the magnetic bearing within the spindle (160), wherein the spindle portion and the rotor portion of the magnetic bearing attract each other; at least one of the rotor portion and the spindle portion of the magnetic bearing includes first and second magnets; the positions of the first and second magnets adjacent to each other, their magnetic vectors are opposite. 26. The pump device according to claim 25, characterized in that, the spindle portion of the magnetic bearing includes first and second magnets (262, 264) that are adjacent to each other and whose magnetic vectors are opposite to each other; The rotor portion includes first and second magnets (282, 284) positioned adjacent to each other with opposite magnetic vectors. 27. The pump device according to claim 25, characterized in that, the spindle portion of the magnetic bearing includes first and second magnets (262, 264) that are adjacent to each other and whose magnetic vectors are opposite to each other; The rotor portion includes ferromagnetic material. 28. The pump unit of claim 27, wherein the ferromagnetic material is soft iron. 29. The pump device according to claim 25, characterized in that, the rotor portion of the magnetic bearing includes first and second magnets (182, 184) that are adjacent to each other and whose magnetic vectors are opposite to each other; The shaft portion includes ferromagnetic material. 30. The pump unit of claim 29, wherein the ferromagnetic material is soft iron. 31. A pump device comprising: a pump casing (110) defining a pump chamber (112), the pump casing having a spindle (130) extending into the pump chamber; a slotted hole (410) a rotor (120) rotatable about the mandrel, the rotor comprising an impeller having at least one blade (121); a rotor portion (180) of magnetic bearings disposed within the non-blade portion of the rotor; and A spindle portion (160) of the magnetic bearing disposed within, wherein the spindle portion and the rotor portion of the magnetic bearing attract each other; at least one of the rotor portion and the spindle portion of the magnetic bearing includes first and second magnets ; The positions of the first and second magnets are close to each other, and their magnetic vectors are opposite. 32. The pump device according to claim 31, characterized in that, the spindle portion of the magnetic bearing includes first and second magnets (262, 264) that are adjacent to each other and whose magnetic vectors are opposite to each other; The rotor portion includes first and second magnets (282, 284) positioned adjacent to each other with opposite magnetic vectors. 33. The pump device according to claim 31, characterized in that, the spindle portion of the magnetic bearing includes first and second magnets (262, 264) that are adjacent to each other and whose magnetic vectors are opposite to each other; The rotor portion includes ferromagnetic material. 34. The pump unit of claim 33, wherein the ferromagnetic material is soft iron. 35. The pump device according to claim 31, characterized in that, the rotor portion (180) of the magnetic bearing includes first and second magnets (282, 284) that are adjacent to each other and whose magnetic vectors are opposite to each other; The spindle portion of the bearing includes ferromagnetic material. 36. The pump unit of claim 35, wherein the ferromagnetic material is soft iron. 37. The pump device according to claim 31, characterized in that the slotted hole (410) comprises at least one helical groove (450) surrounding the hole. 38. The pump assembly of claim 31 wherein the slotted aperture comprises a plurality of slots. 39. The pump assembly of claim 38, wherein each of the plurality of grooves is in the shape of a spiral around the aperture. 40. A pump device comprising: a pump housing (110) delimiting a pump chamber (112), the pump housing having a spindle (130) protruding into the pump chamber; rotatable about the spindle (130) A rotor (120) comprising an impeller having at least one blade (121); a rotor portion (180) of a magnetic bearing disposed within a non-bladed portion of the rotor; a spindle portion of the magnetic bearing disposed within the spindle (160), wherein the spindle portion and the rotor portion of the magnetic bearing attract each other; at least one of the rotor portion and the spindle portion of the magnetic bearing includes first and second magnets; the positions of the first and second magnets adjacent to each other with opposite magnetic vectors; a plurality of drive magnets (122) carried by the non-blade portion of the rotor; and a drive winding (140) in the pump casing, wherein the drive magnets cooperate with the drive winding to rotate the rotor. 41. The pump device according to claim 40, characterized in that the mandrel portion of the magnetic bearing includes first and second magnets (262, 264) that are adjacent to each other and whose magnetic vectors are opposite to each other; The rotor portion includes first and second magnets (282, 284) positioned adjacent to each other with opposite magnetic vectors. 42. The pump device according to claim 40, characterized in that, the spindle portion of the magnetic bearing includes first and second magnets (262, 264) that are adjacent to each other and whose magnetic vectors are opposite to each other; The rotor portion includes ferromagnetic material. 43. The pump unit of claim 42, wherein the ferromagnetic material is soft iron. 44. The pump device according to claim 40, characterized in that, the rotor portion of the magnetic bearing includes first and second magnets (282, 284) that are adjacent to each other and whose magnetic vectors are opposite to each other; The shaft portion includes ferromagnetic material. 45. The pump unit of claim 44 wherein the ferromagnetic material is soft iron. 46. Pump unit according to claim 40, characterized in that the rotor has a slotted hole (410). 47. Pump unit according to claim 46, characterized in that the slotted hole comprises at least one helical groove (450) surrounding the hole. 48. The pump assembly of claim 46, wherein the slotted aperture comprises a plurality of slots. 49. The pump assembly of claim 48 wherein each of the plurality of grooves is in the shape of a spiral around the aperture. 50. A pump device comprising: a pump housing (110) delimiting a pump chamber (112), the pump housing having a spindle (130) protruding into the pump chamber; rotatable around the spindle (130) A rotor (120) comprising an impeller having at least one blade (121); a rotor portion (180) of a magnetic bearing disposed within a non-bladed portion of the rotor; a spindle portion of the magnetic bearing disposed within the spindle (160), wherein the spindle portion and the rotor portion of the magnetic bearing attract each other; at least one of the rotor portion and the spindle portion of the magnetic bearing includes first and second magnets; the positions of the first and second magnets adjacent to each other with opposite magnetic vectors; and at least one of the pump housing and the rotor has a surface configured to create a hydrodynamic bearing between the rotor and the pump housing. 51. The pump device according to claim 50, characterized in that, the mandrel portion of the magnetic bearing includes first and second magnets (262, 264) that are adjacent to each other and whose magnetic vectors are opposite to each other; The rotor portion includes first and second magnets (282, 284) positioned adjacent to each other with opposite magnetic vectors. 52. The pump device according to claim 50, characterized in that, the spindle portion of the magnetic bearing includes first and second magnets (262, 264) that are adjacent to each other and whose magnetic vectors are opposite to each other; The rotor portion includes ferromagnetic material. 53. The pump unit of claim 52 wherein the ferromagnetic material is soft iron. 54. The pump device according to claim 50, characterized in that the rotor portion of the magnetic bearing comprises first and second magnets (282, 284) that are adjacent to each other and whose magnetic vectors are opposite to each other; The shaft part includes ferromagnetic material. 55. The pump unit of claim 54 wherein the ferromagnetic material is soft iron. 56. The pump device as claimed in claim 50, characterized in that the rotor has a slotted hole (410). 57. Pump unit according to claim 56, characterized in that the slotted hole comprises at least one helical groove (450) surrounding the hole. 58. The pump assembly of claim 56, wherein the slotted aperture comprises a plurality of slots. 59. The pump assembly of claim 58 wherein each of the plurality of grooves is in the shape of a spiral around the aperture. 60. The pump apparatus of claim 50 wherein the rotor includes surface features that create the hydrodynamic bearing. 61. The pump assembly of claim 60 wherein the surface features are defined by tapered surfaces. 62. The pump apparatus of claim 50 wherein the pump housing includes surface features that create the hydrodynamic bearing. 63. The pump assembly of claim 62 wherein the surface features are formed by tapered surfaces. 64. The pump apparatus of claim 50 wherein the pump housing and the rotor each include surface features that create the hydrodynamic bearing. 65. The pump assembly of claim 65 wherein the surface features are formed by tapered surfaces. 66. A pump device comprising: a pump housing (110) defining a pump chamber (112), the pump housing having a mandrel (130) protruding into the pump chamber; a spindle magnet assembly (160) of first and second magnets (262, 264), wherein the first and second magnets are positioned adjacent to each other and their magnetic vectors are opposite to each other; the longitudinal axis (362) of the spindle magnet assembly Deviated from the longitudinal axis (390) of the mandrel; and a rotor (120) rotatable about the mandrel (130), the rotor comprising an impeller having at least one blade (121), wherein a bore (410) of the rotor ) slotted. 67. A pump device comprising: a pump housing (110) defining a pump chamber (112), the pump housing having a mandrel (130) protruding into the pump chamber; An arbor magnet assembly (160) of one and second magnets (262, 264), wherein the first and second magnets are positioned adjacent to each other and their magnetic vectors are opposite to each other; a rotor (120) rotatable about the arbor ), wherein the pump housing has a surface configured to at least partially support a hydrodynamic bearing of the rotor when rotating, the rotor comprising an impeller having at least one blade (121); a drive magnet (122). 68. The pump device of claim 67, further comprising: a drive winding (140) carried by the pump housing, wherein the drive magnet cooperates with the drive winding to rotate the rotor.

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